1. Field of the Invention
This invention relates generally to apparatus and methods for providing percutaneous access to an internal body conduit and relates more specifically in one aspect of the invention to apparatus and methods for providing percutaneous access through a gastrostomy tube directly into the stomach of a patient.
2. Discussion of the Prior Art
Tubes are used to provide direct access into internal organs, cavities and other conduits of patients, for a variety of reasons. In one application, a feeding tube is placed in the stomach, duodenum, intestine or colon of a patient in order to provide access for the direct administration of liquid diet or medication. This may be required due to some problem of the patient associated with his ability to chew, swallow, or otherwise ingest nutrients into the stomach through the normal channel including the mouth, throat, esophagus and hiatal valve.
There are four standard methods for placement of a feeding tube. In perhaps the most certain method of placement, an open surgical technique is used. In this method, the feeding tube is placed, under direct visualization, through a surgical incision in the abdominal wall, and into the organ. The organ is then pulled into proximity with the abdominal wall and anchored in a process commonly referred to as approximation. This step of approximation is also performed under direct visualization which allows the surgeon to adjust the anchoring tension in order to achieve the best contact and pressure between the organ and the abdominal wall. While this open procedure best facilitates approximation, it nevertheless leaves the patient with a sizable incision and a long recovery period. This is also a time consuming procedure which must be performed in the operating room. These two factors elevate the cost of the procedure significantly.
In a much less expensive procedure, nasal gastric tubes have been used to provide access to the stomach. In this case a tube is introduced into the nasal cavity of the patient, past the throat and into the stomach. This procedure need not be accomplished in the operating room, so it is much less expensive. Nevertheless, the patient is required to swallow at an appropriate time in order to pass the tube through the throat. If this passage is not accurately accomplished the tube can lodge in the lungs causing the patient to undergo considerable trauma and even producing pneumonia. Some practitioners are more skilled at this process of tube passage than others, but even these practitioners have a success rate of only about 50%. A nasal gastric tube must be taped to the side of the patient's face, often leading to sever adhesive burns. Also, in some cases the patient must be restrained in order to prevent the self-removal of this tube. Nasal gastric tubes are generally for short term use. They are usually converted to gastrostomy feeding tubes if the period needs to be extended.
In a procedure commonly referred to as percutaneous endoscopic gastrostomy (PEG) a gastroscope is placed through the mouth of the patient and into the stomach. The scope is then deflected toward the abdominal wall where the light from the scope helps identify the ideal location to access the stomach. Using a percutaneous introducer, a guidewire is inserted into the stomach through the abdominal wall; anchors are then placed across the abdominal wall and into the stomach. The tip of the guidewire is grasped through the working channel of the scope and pulled with the scope through the patient's mouth. A feeding tube is then attached to the guidewire using sutures and is pulled into place as the guidewire is withdrawn from the abdomen.
The disadvantage of this percutaneous endoscopic procedure is that the approximation of the abdominal wall with the stomach is performed without visualization. If too much tension is applied to the anchors, circulation is impaired leading to tissue necrosis. If too little tension is applied to the anchors, poor sealing contact results. In either case leakage of gastric juices around the tube can lead to inflammation and infection.
Radiologic placement has also been attempted under fluoroscopic vision. A percutaneous introducer is placed in the stomach through the abdominal wall and anchors are suitably applied. The guidewire is introduced into the stomach through an introducer which is then removed. Successive dilators can then be introduced over the guidewire until a suitably sized split-sheath can be placed. The feeding tube is then introduced through the sheath and into the stomach. Ultimately the sheath is retracted and split apart around the feeding tube. This procedure also suffers from the lack of visualization during the approximation step.